Various key model rearrangements of molecular cation radicals in mass spectrometers when subject to scrutiny as to their isotope effects, temperature dependencies of their rates, and stereochemistry behave consistently with the view that their structures and energies are, within the limits of our probes, unperturbed from the characteristics of their neutral precursors. Four major research directions flow from this: (1) quantitative conformational analysis of comparable rearranging charged radicals in mass spectrometers and in solution; (2) development of synthetically useful reactions modeled after reactions in mass spectrometers: (3) creating new ways to analyze complex molecules by mass spectrometry; (4) firming the connection between mass spectrometry and thermal free radical chemistry and the resulting recognition of parallel processes.